The present invention relates to panel or wall mounted speaker units, and more particularly to an improved system for mounting speaker units of intercoms and the like to a wall panel having a suitable opening formed therein.
Speaker units for intercoms and distributed sound systems are commonly mounted to gypsum wallboard panels and other wall members of building structures. In typical frame construction, an opening for receiving a body portion of the speaker unit is formed in the panel between supporting studs, the body portion projecting within a blind cavity bounded by the studs, the panel, and other wall paneling that is fastened to the studs opposite the panel having the opening. In the past, the speakers were often directly fastened to the panels by screw fasteners. However, gypsum wallboard provides a poor anchor for screw fasteners. Thus the mounting preferably involves clamping the panel between a bezel flange of the unit and movable members that contact hidden surfaces of the panels.
In one implementation, the clamping is effected by a plurality of swinging arms that are initially positioned within an outline of the body portion for permitting the speaker unit to be placed with the bezel flange contacting the panel, the arms being mounted on screw fasteners that are accessible from a front portion of the speaker unit. Initial rotation of each fastener causes the corresponding arm to be pivoted such that the arm extends behind the panel outside of the opining; continued rotation causes the arm to be drawn toward the bezel flange for clamping the panel between the arm and the flange.
In another implementation, clamping is effected by a pair of beam members that extend across the opening, the beam members being drawn against the back side of the panel by screw fasteners that are initially loosened sufficiently for permitting the beam members to be jockeyed into position behind the panel as the speaker unit is positioned with the bezel flange against the front of the panel. In this implementation, the screw fasteners connecting the beam members to the body of the speaker unit must be spaced a significant distance from at least one end of the body for permitting the speaker unit to be temporarily located with a portion of the panel extending between the body and the beam members, so that opposite ends of the beam members can be jockeyed behind the panel. Also, the beam members are typically formed having shallow cross-sectional shapes for permitting the speaker unit to be mounted as described above in walls having relatively close spacing between opposite panels thereof, and for facilitating low cost manufacture of the beam members. Consequently, the speaker units of the prior art having clamp beams as described herein are subject to significant flexural deformation of the beam members during installation, to the extent that panel-contacting ends of the beam members contact the panels only at boundaries of the opening. Unfortunately, the panels are subject to crumbling and ends of the beam members are subject to being displaced toward or into the opening when the clamping force is applied by the fasteners, even when additional fasteners are employed following preliminary tightening of the initial complement of fasteners connecting the beam members to the body.
In a recent development, one configuration of the clamping beams has been provided with sloping feet that initially contact the back side of the panel at extremities only of each beam, with the feet coming into full contact with the panel only at a predetermined bending deflection of the beams. Unfortunately, it is difficult or impossible to determine the contact orientation of the feet during installation of the speaker unit when the space behind the panel is not visible, being covered by the speaker unit. Thus the clamping is likely to involve edge-contact only by the feet against the panel, subjecting the panel to possible damage from excessive concentrations of force. Further, edge contact by the feet is unavoidable at clamping forces less than those producing the desired predetermined deflection of the beams, resulting in some damage to panels formed of many typical materials such as gypsum and low-density pressed fiberboard by edge contact with the feet. It is also possible that the backside of the panel is uneven such that edge or corner contact results even when a desired deflection is imparted to the beam.
Efforts directed to tightening the clamping fasteners to a predetermined torque for effecting the predetermined bending deflection are uncertain at best, in that the beams can be clamped using from two to six fasteners apiece, the shape of the beam deflection being markedly affected by the distribution of clamping forces along the beam. Moreover, the clamping forces generated by the various fasteners is only very roughly proportional to the applied torque, particularly in the usual case of the customary self-threading fasteners engaging molded plastic clamp beams.
Thus there is a need for speaker units having beam clamps for mounting to blind panels, the clamps making full contact with the panel regardless of bending deflections of the beams during and after installation of the speaker units.